IYDS: International Youth Development Study

The International Youth Development Study (IYDS) is a long-term study that looks at the development of healthy and problem behaviours among young people in the state of Victoria, Australia and the state of Washington, United States. IYDS is one of the first studies designed to examine whether or not differences in Australian and American cultures and schools affect youth development. The study began in 2002. The original sample included approximately 1000 students at each of three year levels in both Victoria and Washington, giving a total of nearly 6000 participants. The study continues to follow-up participants into adulthood.

Data are available according to study protocols, namely: approval of proposal by Principal Investigators; Data Sharing Collaboration Agreement read and agreed to by all parties, Fair Use Agreement signed by applicant and Principal Investigators.

Study focus (e.g. social development)

Risk and protective factors, as well as healthy and problem behaviours in young people including substance use, delinquency, violence, risky sex, depression and self-harm.

Sampling frame

In 2002, a two-stage cluster sample design was used to recruit students in both states (Victoria, Australia and Washington State, USA). In the first stage, schools were selected at random, based on a probability proportional to grade-level size from a stratified sampling frame of all schools in Victoria (government, Catholic and independent) and Washington (public, private and alternative). At Stage 2, single intact classes from each school for the selected grade level (Grade 5 (Y), 7 (M) or 9 (O)) were chosen at random; in a few cases, 2 classes from different year levels were randomly chosen at a school.

Study type (e.g. randomised control trial, cohort, case-control)

Longitudinal cohort study

Year commenced

2002

Ongoing recruitment?

No

Commencement sample (N)

AUS: 2884
USA: 2885
(Total 5,769)

Annual attrition rate (%)

Of the total eligible sample, 98.65% were re-surveyed in Wave 2 (2003),
97.59% in Wave 3 (2004),
86.93% in Wave 4 (2006),
89.2% in Wave 5 (2007), and
85.3% in Wave 6 (2008).
For the young adult follow up surveys, 84% of the total eligible sample were surveyed in follow up 1 (2010),
83% in follow up 2 (2012), and
87% in follow up 3 (2014).